using raster data · 2009. 8. 10. · b 2 r –invisible to end users • the raster is a table; a...

Using Raster DataUsing Raster Data

Matthew BakerMatthew BakerESRI Educational ServicesESRI Educational ServicesESRI Educational ServicesESRI Educational Services

Redlands, CARedlands, CA

11

Lesson OverviewLesson Overview•• Raster dataRaster data•• Raster in a geodatabaseRaster in a geodatabaseRaster in a geodatabaseRaster in a geodatabase

––Datasets Datasets ––CatalogsCatalogs

Geodatabase

gg––AttributesAttributes

UC 2006 Tech SessionUC 2006 Tech Session 22

What is a RasterWhat is a RasterA matrix of cells/pixels/squaresA matrix of cells/pixels/squares•• A matrix of cells/pixels/squaresA matrix of cells/pixels/squares

–– Cells store a number representing Cells store a number representing the feature found in the cell area the feature found in the cell area

•• AdvantagesAdvantages•• Advantages Advantages –– Simpler data modelSimpler data model–– Faster processing and displayFaster processing and display

Additi l l ti t lAdditi l l ti t lReal world

–– Additional analytic toolsAdditional analytic tools–– Better for unbounded phenomena Better for unbounded phenomena

(like soil pH and elevation)(like soil pH and elevation)•• DisadvantagesDisadvantages•• DisadvantagesDisadvantages

–– GeneralizationGeneralization–– Loss of feature uniquenessLoss of feature uniqueness

As vector

A t


As raster

Features as rasterFeatures as raster

•• Features lose uniqueness with raster representationFeatures lose uniqueness with raster representation–– A line becomes a collection of cells, not one featureA line becomes a collection of cells, not one feature

VectorVector

Points Lines Polygons

Raster


Raster cells/pixelsRaster cells/pixels•• Cell properties & characteristicsCell properties & characteristicsCell properties & characteristicsCell properties & characteristics

–– Arranged in a matrix of columns and rowsArranged in a matrix of columns and rows–– Each cell has a numeric Each cell has a numeric valuevalue

•• Integer Integer •• Floating pointFloating point•• NoDataNoData

–– Cells may have one or more Cells may have one or more values/bandsvalues/bandsEach cell is independentEach cell is independent–– Each cell is independentEach cell is independent

1000 rows

UC 2006 Tech SessionUC 2006 Tech Session 551000 columnsPixel

Raster BandsRaster Bands

•• Defined as layer of cell values for one variableDefined as layer of cell values for one variable•• Raster can consist of one or many bandsRaster can consist of one or many bands

–– SingleSingle--bandband•• Single variableSingle variable

–– MultiMulti--bandband•• Multiple variables per bandMultiple variables per band•• Each band coversEach band covers

same areasame area•• Stored inStored in

Aerial PhotoAerial Photo

Stored inStored inone raster datasetone raster dataset

•• Up to three bands canUp to three bands canbe displayed togetherbe displayed together

SatelliteSatellite


Satellite Image

Satellite Image

Raster coordinate systemsRaster coordinate systems•• Both cell matrix and CartesianBoth cell matrix and CartesianBoth cell matrix and CartesianBoth cell matrix and Cartesian

s Matrix

y-ax

is

columns0 1 2 3 . . .012

Matrix/Cartesian origin• Cells located byrow/column position

• Origin at upper left

ows

23

. . .

Cell (8,9)Origin at upper left

• Rows and columnsalways perpendicular

ro Cartesian• Cells located by x,y

M i t t

Map projection origin (0,0)x-axis

• May register toa map projection

• Used in ArcMap


Map projection origin (0,0)

ResolutionResolution

•• Rasters generalize spatial dataRasters generalize spatial data•• A function of cell size (smaller cells = higher resolution)A function of cell size (smaller cells = higher resolution)

Impacts acc rac processing speed storage spaceImpacts acc rac processing speed storage space•• Impacts accuracy, processing speed, storage spaceImpacts accuracy, processing speed, storage space

True lake area 745,322 m2

100 m 400 m200 mCell size 100 m 400 m200 m

12x12 3x36x674 519

Cell size

MatrixLake cells


740,000 m2 800,000 m2760,000 m2Area

Raster formatsRaster formats

•• The format is how cells are stored in a rasterThe format is how cells are stored in a raster•• ArcGIS supports dozens of raster formats ArcGIS supports dozens of raster formats

–– Various image formats Various image formats (SID, IMG, TIF, etc.)(SID, IMG, TIF, etc.)

–– ESRI grid and grid stackESRI grid and grid stack–– ESRI ArcSDE raster ESRI ArcSDE raster

grid

–– ESRI raster datasetESRI raster dataset–– ESRI raster catalogESRI raster catalog

•• All may be managed in ArcCatalog All may be managed in ArcCatalog SID•• All may be used with Spatial Analyst toolsAll may be used with Spatial Analyst tools

gif


TIF imgbmp

Raster format essentialsRaster format essentials

•• All raster formats are basically the same All raster formats are basically the same –– Cells organized in a matrix of rows and columnsCells organized in a matrix of rows and columns

Content is more important than format: Data or picture?Content is more important than format: Data or picture?–– Content is more important than format: Data or picture?Content is more important than format: Data or picture?

columnsro

ws Raster data

• Elevation• Landuse codes

Raster Pictures• Scanned maps• Satellite images

Elevation

• Population densityGood for analysis• Slope from elevation

Satellite images(unclassified)

• Photos of buildingsGood for mapping

Good for mapping• Thematic layers• Derivative products

• BackgroundsGood for attributes• Picture of house

Scanned map


A

p(like shaded relief) Bad for analysis

Raster attribute tablesRaster attribute tables

•• All singleAll single--band integer rasters have band integer rasters have virtualvirtual tablestables–– Created on the fly by ArcGISCreated on the fly by ArcGIS–– Support ArcMap joins and relatesSupport ArcMap joins and relates Virtual tablejj

•• Integer ESRI grids have real tablesInteger ESRI grids have real tables–– Support ArcMap joins and relatesSupport ArcMap joins and relates–– Support userSupport user--defined fieldsdefined fields

for TIF image

Suppo t useSuppo t use de ed e dsde ed e ds–– Use fields in analysis and queriesUse fields in analysis and queries


Tables have one record for each unique value except NoData.

ArcGIS raster supportArcGIS raster support

•• Core support for raster in:Core support for raster in:––ArcMapArcMap

•• Draw, query, Draw, query, georeferencegeoreference––ArcCatalogArcCatalog

•• Copy rename deleteCopy rename delete•• Copy, rename, deleteCopy, rename, delete––ArcToolboxArcToolbox

•• Convert, project, merge, clipConvert, project, merge, clip––GeodatabaseGeodatabase

•• Storage as:Storage as:Raster datasets orRaster datasets or––Raster datasets or Raster datasets or

––Raster catalogsRaster catalogs

** Spatial Analyst extension adds more functionality andSpatial Analyst extension adds more functionality and* * Spatial Analyst extension adds more functionality and Spatial Analyst extension adds more functionality and analysisanalysis


Geodatabase raster storage optionsGeodatabase raster storage options

•• Raster datasetRaster datasetAn alid raster formatAn alid raster format–– Any valid raster formatAny valid raster format

R t t lR t t l•• Raster catalogRaster catalog–– A collection of raster datasetsA collection of raster datasetsstored in a tablestored in a table(like digital aerial(like digital aerial(like digital aerial (like digital aerial photographs)photographs)

•• Raster attributeRaster attributeUse for feature attributesUse for feature attributes–– Use for feature attributesUse for feature attributes

–– One field of type raster per One field of type raster per tabletable


PyramidsPyramids•• Reduced resolution copiesReduced resolution copies•• Reduced resolution copiesReduced resolution copies•• Pixel size doubles at each levelPixel size doubles at each level•• Improves performanceImproves performancep pp p

–– Returns best resolution Returns best resolution for screen displayfor screen display

–– Returns about same numberReturns about same number3rd (8 m)

of pixels as scale changesof pixels as scale changes–– Analysis on originalAnalysis on original 2nd (4 m)

1st (2 m)

1 meter2x2 pixel blocks


Rasters in a personal geodatabaseRasters in a personal geodatabase

MM•• Manages rastersManages rasters•• Stores a reference to external fileStores a reference to external file--based rastersbased rasters

–– Microsoft Access MDB file is limited to 2 GB total sizeMicrosoft Access MDB file is limited to 2 GB total sizeP id t li d t tP id t li d t t–– Provides centralized access to rastersProvides centralized access to rasters

•• Manages raster datasetsManages raster datasets–– Single rasterSingle raster

manages raster catalogsmanages raster catalogspGDB

•• manages raster catalogsmanages raster catalogs–– Collection of rastersCollection of rasters

Elevation

TopoMap


Rasters in a file geodatabaseRasters in a file geodatabase

•• Stores raster catalogs and raster datasets internallyStores raster catalogs and raster datasets internally–– Up to one terabyte for each raster dataset or raster catalogUp to one terabyte for each raster dataset or raster catalog–– Provides centralized access to rastersProvides centralized access to rasters

•• File Geodatabase rasters intended for:File Geodatabase rasters intended for:–– single user and small work groupssingle user and small work groups–– Some readers and one writerSome readers and one writer fGDB

Raster catalog

Raster dataset

fGDB

Raster catalog


Rasters in an ArcSDE geodatabaseRasters in an ArcSDE geodatabase

•• Stored internally Stored internally •• ArcSDE subdivides raster ArcSDE subdivides raster

Block 0 1 2 3 4 5 6COL_NBR

into into blocksblocks for storagefor storage–– Size set by userSize set by user–– Automatic and requiredAutomatic and required

0

1

2BR

–– Invisible to end usersInvisible to end users•• The raster is a table; aThe raster is a table; a

block is a row in the tableblock is a row in the table

2

3

4

ROW_NB

•• Provides faster access to dataProvides faster access to data–– ArcSDE returns blocks for visible areaArcSDE returns blocks for visible area–– Improves display performanceImproves display performance

5

p p y pp p y p

0 0

0 1

ROW COL


0 10 2

Geodatabase raster datasetsGeodatabase raster datasetsPersonal Geodatabase

storage•• A single raster in a A single raster in a geodatabasegeodatabase

storage

–– Good for analysis and Good for analysis and mappingmapping

–– SeamlessSeamlessSeamlessSeamless–– Fast display at any scaleFast display at any scale–– May load many rasters May load many rasters y yy y

into one raster dataset into one raster dataset (mosaic)(mosaic)


Image1 Image2 Mosaic

Mosaic cell overlap optionsMosaic cell overlap options

Si tiSi ti•• Six optionsSix options•• Combine multiple Combine multiple rastersrasters into oneinto one

–– Mosaic and Mosaic To New Raster toolsMosaic and Mosaic To New Raster tools

FIRST 60 MEAN 60MINIMUM 60FIRST240 0

12060

60

MEAN 240 0

12060

30

MINIMUM240 0

12060

0

120

LAST240 0

12060

180

BLEND240 0

12060

120

MAXIMUM240 0

12060

240 0

240

0

240 0

240 to 120

0 to 60

240 0

240

60


240 240 to 120240

Discrete Continuous

Geodatabase raster catalogsGeodatabase raster catalogs

A collection of raster datasetsA collection of raster datasets•• A collection of raster datasets A collection of raster datasets –– Behave as one, but storedBehave as one, but stored

separately (rows in a table)separately (rows in a table)–– May overlap, have gaps,May overlap, have gaps,

different cell sizes, bit depthsdifferent cell sizes, bit depths–– Must have same spatial reference Must have same spatial reference M

–– Good for archives, display, and mappingGood for archives, display, and mapping

Managed

Unm

an


naged

Managing raster catalogs in ArcCatalogManaging raster catalogs in ArcCatalog

C t t t bC t t t b•• Contents tabContents tab–– Properties, Geography, Metadata, and Bands preview optionsProperties, Geography, Metadata, and Bands preview options

Wireframepreview

Wireframepreview


Query builderQuery builder Preview dropdownPreview dropdown

A

Raster attributesRaster attributes

•• Pointer stored as a value ion a Raster field Pointer stored as a value ion a Raster field –– View with the Identify tool or in the attribute tableView with the Identify tool or in the attribute table


Raster management tools Raster management tools -- GeoprocessingGeoprocessing•• General raster databaseGeneral raster database•• General raster database General raster database

management toolsmanagement tools–– Copy, paste, delete, calculate Copy, paste, delete, calculate

statistics set spatial referencestatistics set spatial referencestatistics, set spatial referencestatistics, set spatial reference•• Data organization/preparationData organization/preparation

–– MosaickingMosaickingRaster catalogsRaster catalogs–– Raster catalogsRaster catalogs

•• Raster data storageRaster data storage–– PyramidsPyramids

GDB t h lGDB t h l–– GDB technologyGDB technology


ExerciseExercise

•• Explore raster storageExplore raster storage•• Create a raster datasetCreate a raster dataset•• Create a raster catalogCreate a raster catalog•• Use rasters as feature attributesUse rasters as feature attributes•• Use rasters as feature attributesUse rasters as feature attributes


Questions ?Questions ?


using raster data · 2009. 8. 10. · b 2 r –invisible to end users • the raster is a table; a...

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